We report the case of a 17-year-old male with a testicular tumor and high serum levels of alpha-fetoprotein. The patient was treated with surgery followed by combination chemotherapy with bleomycin, etoposide, and cisplatin. Histologic examination showed features of a mixed germ cell tumor composed of mature teratoma, immature teratoma, embryonal carcinoma, yolk sac tumor, and polyembryoma. He is currently well, and his serum levels of alpha-fetoprotein have been normal more than 5 months after treatment. His brother, aged 17 years at the time, had a similar tumor removed from the right testicle 5 years previously.